Bis(4-nitroanilines) in interactions through a π-conjugated bridge: conformational effects and potential molecular switchesElectronic supplementary information (ESI) available. CCDC 1003266 (PNA). For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7nj02622f

Two molecules, 2,2′-(1,4-phenylenebis(ethyne-2,1-diyl))bis(4-nitroaniline) ( PNA ) and 2,2′-(1,4-phenylene-bis(ethyne-2,1-diyl))bis( N , N -diethyl-4-nitroaniline) ( PDNA ), built up from two p -nitroaniline " push-pull " nonlinear optical (NLO) chromophores slightly conjugated through a 1...

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Hauptverfasser: Guerrero, Tomás, Santillan, Rosa, García-Ortega, Héctor, Morales-Saavedra, Omar G, Farfán, Norberto, Lacroix, Pascal G
Format: Artikel
Sprache:eng
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Zusammenfassung:Two molecules, 2,2′-(1,4-phenylenebis(ethyne-2,1-diyl))bis(4-nitroaniline) ( PNA ) and 2,2′-(1,4-phenylene-bis(ethyne-2,1-diyl))bis( N , N -diethyl-4-nitroaniline) ( PDNA ), built up from two p -nitroaniline " push-pull " nonlinear optical (NLO) chromophores slightly conjugated through a 1,4-phenylenebis(ethyne-2,1-diyl) bridge have been synthesized and fully characterized. The crystal structure of PNA reveals that the ground (off) state conformation corresponds to the centrosymmetric anti-conformer in which the molecular hyperpolarizability ( β ) is equal to zero. A computational investigation reveals that, once submitted to an intense electric field ( E ), the two p -nitroaniline subunits are gradually aligned in the direction of the field with the appearance of a metastable (on) state ( β ≠ 0, when E = 0), stabilized by conjugation. A loop of hysteresis is observed during the on off cycles leading to a form of molecular bistability. The NLO response of PNA has been investigated at different field intensities by the electric-field induced second-harmonic (EFISH) technique to provide experimental evidence for this behavior. DFT computation suggests that two dipolar chromophores in rotation around an organic bridge could be aligned by an electric field.
ISSN:1144-0546
1369-9261
DOI:10.1039/c7nj02622f